After clinching a deal with a Chinese battery maker in 2016, James Brown figured bankers would be eager to fund his new lithium mine. Altura Mining Ltd. was racing to ship the raw material from Australia to the world’s biggest electric vehicle market as demand was surging.

Instead, while lithium prices kept rising, Brown spent a Christmas holiday cold-calling lenders and jetted around the globe to raise the money. Eventually, Minneapolis-based Castlelake LP, a private equity firm, helped arrange $110 million in bonds. But there was a catch: an interest rate as high as 15 percent, or almost double what banks normally charge for more conventional mining ventures.

“We’d been trying banks we’d known for years,” said Brown, Altura’s managing director, who previously spent 22 years with coal producer New Hope Corp. “They said: Guys we love it, we just don’t have a mandate (for lithium). If you came to us with coal, gold or iron ore, you’d have no worries.”

Despite bullish forecasts for global demand — especially with accelerating production of electric vehicles — lithium may have a funding problem. Banks are wary, citing everything from the industry’s poor track record on delivering earlier projects to a lack of insight into a small, opaque market.

Without more investment, supplies of the commodity could remain tight, sustaining a boom that already has seen prices triple since 2015.